The stock fell as much as $18.95 to $38 in extended trading at 5 p.m. New York time after the announcement, the biggest drop in more than a decade. Coinstar slipped 28 cents to $56.95 in regular Nasdaq Stock Market trading. The company said yesterday in a statement that it plans to report full results on Feb. 3.

Coinstar has agreed to a 28-day delay in receiving the latest DVD releases from Hollywood, giving studios a four-week window to sell their latest movies before offering them for rental in Redbox kiosks. The delay requires management to do a better job of selecting titles to keep customers renting while they wait for newer releases, said Eric Wold, an analyst at Merriman Curhan Ford & Co. in New York.

“They made the wrong decisions on what titles to stock,” said Wold, who rates the shares “buy” and doesn’t own them. “There’s a learning process.”

The company, which has taken sales from traditional retailers such as Blockbuster, previously exceeded analysts’ net-income estimates for eight straight quarters, according to data compiled by Bloomberg.

“We underestimated the impact that the delay would have on demand during the fourth quarter,” Chief Executive Officer Paul Davis said in the statement. “We also expected much better performance from Blu-ray.”